I have an encrpted LVM install with debian testing and ext3. I was running out of space yesterday on / so I reduced my /home/ and was able to extend my root partition.
It would not let me do the reduce online but would let me to lvextend online. I had to log on as root, unmount /home/ reduce it and extend /.
It said that this is not supported when I have read that LVM does support online reduce with ext3.